fine (i.e. not coarse)
緻 centers on extreme fineness and precision, like tightly woven thread or a meticulously detailed result. The core idea is something refined and not coarse.
緻 combines 糸 (thread) with 致, which likely contributes the sound and the idea of reaching a detailed state. The character suggests the fineness of tightly spun thread.
The left side is thread 糸, and the right side 致 looks like someone reaching a precise arrangement. Imagine weaving thread so tightly that the fabric becomes perfectly fine and smooth.
For チ, picture a tiny, fine thread being pulled through the eye of a needle with a soft 'chi' sound: chi -> チ, like the delicate whisper of something extremely fine.